Devices such as barcode scanners are used in various inventory applications. In some configurations, these barcode scanners use internal auto-focus cameras to capture images of barcodes and other scannable indicia. While auto-focus camera systems are flexible enough to be used in different applications, there are considerable operational delays as camera systems focus on different objects and different distances. Furthermore, the need for accurate and fast focusing on varied objects adds considerable processing complexity and mechanical componentry to these camera systems, all of which increase costs.
Auto-focus cameras typically have lens apertures much larger than fixed focus systems. As a result, auto-focus cameras are known to have shallower depth of focus for any particular focus setting. For conventional scanning applications, the shallower depth of focus is not a problem as the system focuses on a barcode. In some environments of use, however, in particular the barcode scanning mode termed hands-free operation, there is typically not enough time for a conventional auto-focus camera system to focus fast enough to acquire an image of sufficient image focus quality to allow for accurate decoding of a barcode. In hands-free operation mode, the user or a conveyor system is swiping, dragging, or otherwise moving barcode objects in front of the barcode scanner at very high scan rates, scan rates that are at times (if not often) faster than the auto-focus time of the system. Furthermore, the working distance in a hands-free operation mode can be large, i.e., the distance range between the barcode reader and the plane of the barcode to be scanned can vary greatly from one object to the next. The larger the working distances, the longer it takes for the auto-focus camera system to focus over the entire working distance.
Accordingly, there is a need for focusing imaging capture systems applicable to barcode readers.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.